If there's a real need for having multiple callout protocols, let's
have a discussion and see whether there's WG consensus to do so.
Otherwise, I'd suggest we focus on getting a single callout

protocol

done right, and base the companion documents around this protocol.
Leaving too many options seems like a simple way to overcome
controversy and to make everybody happy, but it might not always be
the best choice in technical design.

I agree; you may have misinterpreted what we are after:
OPES architecture already assumes that adaptation can be done
by means other than OCP. Thus, we are not increasing
complexity or adding anything really new. We are simply
making a statement that OPES framework (tracing, bypass, and
such) should not depend on OCP because OCP is not the only
allowed way to do adaptation!
The fact that SOAP may be used as a callout protocol is just
a side-effect of the above statement. We will not focus on
SOAP. We will focus on "our" OCP. "How to use SOAP as an OPES
callout protocol" draft may (should??) end up having a single
normative sentence:
use "as is"
Does this approach work for you?
Alex.